Atomic-Scale Surface Segregation in Copper-Gold Nanoparticles,Physical Review Letters

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Atomic-Scale Surface Segregation in Copper-Gold Nanoparticles
Physical Review Letters ( IF 8.1 ) Pub Date : 2023-06-09 , DOI: 10.1103/physrevlett.130.236201
Grégoire Breyton _{1,

2} , Hakim Amara _{1,

2} , Jaysen Nelayah ₁ , Jérôme Creuze ₃ , Hazar Guesmi ₄ , Damien Alloyeau ₁ , Guillaume Wang ₁ , Christian Ricolleau ₁

Affiliation

We combine electron microscopy measurements of the surface compositions in Cu-Au nanoparticles and atomistic simulations to investigate the effect of gold segregation. While this mechanism has been extensively investigated within Cu-Au in the bulk state, it was never studied at the atomic level in nanoparticles. By using energy dispersive x-ray analysis across the (100) and (111) facets of nanoparticles, we provide evidence of gold segregation in

{Cu}_{3} Au

and

{CuAu}_{3}

nanoparticles in the 10 nm size range grown by epitaxy on a salt surface with high control of the nanoparticles morphology. To get atomic-scale insights into the segregation properties in Cu-Au nanoparticles on the whole composition range, we perform Monte Carlo calculations employing

N

-body interatomic potentials highlighting a complete segregation of Au in the (100) and (111) facets for gold nominal composition above 70% and 60%, respectively. Furthermore, we show that there is no size effect on the segregation behavior since we evidence the same oscillating concentration profile from the surface to the nanoparticle’s core as in the bulk. These results shed new light on the interpretation of the enhanced reactivity, selectivity, and stability of Cu-Au nanoparticles in various catalytic reactions.

中文翻译：

铜金纳米颗粒的原子级表面偏析

我们结合电子显微镜测量 Cu-Au 纳米粒子表面成分和原子模拟来研究金偏析的影响。虽然这种机制已在块体状态的 Cu-Au 中得到了广泛研究，但从未在纳米颗粒的原子水平上进行过研究。通过对纳米颗粒的 (100) 和 (111) 面进行能量色散 X 射线分析，我们提供了金偏析的证据

铜_{3} 金

和

{金铜}_{3}

通过在盐表面外延生长的 10 nm 尺寸范围的纳米颗粒，对纳米颗粒的形态进行高度控制。为了从原子尺度上了解 Cu-Au 纳米颗粒在整个成分范围内的偏析特性，我们使用以下方法进行蒙特卡罗计算：

氮

-体原子间势突出显示金在 (100) 和 (111) 面上的完全偏析，金名义成分分别高于 70% 和 60%。此外，我们表明，分离行为不存在尺寸效应，因为我们证明了从表面到纳米颗粒核心与本体中相同的振荡浓度分布。这些结果为解释 Cu-Au 纳米粒子在各种催化反应中增强的反应性、选择性和稳定性提供了新的线索。

更新日期：2023-06-09

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